1. Marilyn was relatively poorly paid. Jane Russell was paid around 10 times as much as Marilyn when they co-starred in Gentlemen Prefer Blondes. Her salary for her final unfinished film, Something’s Got to Give, was $100,000. Compare that with Elizabeth Taylor, who was getting a million dollars for Cleopatra; or even Marilyn’s co-star in the film, Dean Martin, who was on $500,000. Today, her estate makes around five million dollars a year.

2. But she died having become a million-dollar movie star. In 1962 she was fired by Twentieth-Century Fox from the production of Something’s Got to Give because of her chronic lateness and no-shows (she didn’t appear for the first two weeks of filming). But on August 1, four days before her death, she was rehired by Fox on a $1million, two-picture deal.

3. She found it almost impossible to learn lines, and took 60 takes to deliver the line “It’s me, Sugar”, in Some Like it Hot.

4.She was Playboy’s first Sweetheart (later Playmate) of the Month, in 1953. Marilyn had been paid $50 to model for the picture in 1949; Hugh Hefner bought it for $500.

5. Several of the burial vaults near to Marilyn’s have been put on sale. When Elsie Poncher, the widow of the man in the vault above Marilyn’s, put his space up for sale on eBay, she received dozens of bids, including one for £2.8million.

6. Hugh Hefner owns the burial vault next to Marilyn at the Westwood Memorial Park in Los Angeles. He bought it in 1992 for £50,000.

Marilyn Monroe on the cover of the first issue of 'Playboy'

7. She went by many names. On her birth certificate she is Norma Jeane Mortenson; she was baptised Norma Jeane Baker; she modelled under the names Jean Norman and Mona Monroe; her initial idea for a screen name was Jean Adair; she signed into hotels as Zelda Zonk and into a psychiatric clinic as Faye Miller. She only legally changed her name to Marilyn Monroe in March 1956, when she was already a star.

8. She was placed with 11 sets of foster parents after her mother, Gladys, was institutionalised. She also spent almost a year in the Children’s Aid Society Orphanage in Los Angeles.

9. Goya was her favourite artist: “I know this man very well, we have the same dreams, I have had the same dreams since I was a child.”

Marilyn Monroe poses over the updraft of a New York subway grating during a photo session to promote the film The Seven Year Itch in September 1954 Credit: Matty Zimmerman

10. Marilyn became a Christian Scientist at the age of 18; later in her life she dabbled in alternative spiritualities, including Anthroposophy, the philosophy espoused by Rudolf Steiner. She converted to Judaism before her 1956 marriage to Arthur Miller.

11. Her weight went up and down so dramatically during the filming of The Prince and the Showgirl that the costume designer, Beatrice Dawson, had to create facsimile dresses in different sizes. “I have two ulcers from this film,” she said, “and they’re both monogrammed MM.”

12. She was rarely without an acting coach. Her first, Natasha Lytess, worked with her for six years and 22 films, clashing with directors, whose authority she challenged, and studio heads, who paid her bills. (Marilyn also paid her a wage – and settled her £11,000 debt at the dentist.)Later, Paula Strasberg took Lytess’s role; unlike Lytess, who tried to direct Marilyn’s every movement from behind the camera, Strasberg was consulted between takes. To coach Marilyn in The Prince and the Showgirl, she was paid $25,000 – as much as some of the featured actors were getting.

Marilyn Monroe and Laurence Olivier on the set of The Prince and the Showgirl

13. For 20 years after Marilyn’s death, Joe DiMaggio arranged to have roses sent to her crypt three times a week.

14. In January 2011, Authentic Brand Groups bought the licensing rights to the Marilyn Monroe estate, for a price in the range of $30million. “On the media and entertainment side,” said the company’s chief executive, Jamie Salter, “I think she’s got a career in front of her, just based on technology.”

15. At the 1999 auction of Marilyn’s effects, her white baby grand piano was bought by Mariah Carey, the singer, for $662,500. (The estimate had been $10,000-$15,000.) The piano had been bought by Marilyn’s mother, and sold after she had her breakdown, but Marilyn eventually found it and bought it back, keeping it with her until her death.

16. There was an open casket at her funeral. She wore an apple green Pucci sheath dress made of nylon jersey and a platinum wig (her head had been partially shaved during the autopsy).

17. She was thought to have been planning to remarry Joe DiMaggio at the time of her death. After the failure of their marriage, DiMaggio had undergone therapy, stopped drinking alcohol and expanded his interests beyond baseball: he and Marilyn read poetry together in these later years.

Marilyn Monroe and Joe DiMaggio Credit: Reuters

18. Marilyn’s beaded Jean Louis gown, worn when she sang Happy Birthday to President Kennedy, was sold in 1999 for £820,000. At the time it was the record price for a single item of clothing, until Marilyn’s billowing white Seven Year Itch dress was put up for sale by Debbie Reynolds in 2011, where it made £2.8 million.

19. Marilyn owned many dogs during her life; her last was a Maltese terrier given to her by Frank Sinatra, which she named Maf (short for Mafia Honey). At the Christie’s sale in 1999, two Polaroids of Maf sold for £220,000.

20. Marilyn left 75 per cent of her estate to the Strasbergs; eventually this fell to Anna Strasberg, Lee Strasberg’s third wife. She vetoes the use of all images in which Marilyn wears fur, citing Marilyn’s love of animals as a reason.

21. The Anna Freud Centre, a child therapy clinic in Hampstead, north London, owns the remaining 25 per cent of Marilyn Monroe’s estate. The centre was left its share by Dr Marianne Kris, one of Marilyn’s therapists, and the original beneficiary of her will.

22. Before her marriages to Joe DiMaggio and Arthur Miller, Marilyn was married to James Dougherty. She was 16 when they tied the knot. Dougherty, who later became a detective in the LAPD, was forbidden by his second wife from going to see any of Marilyn’s films.

Marilyn Monroe with her first husband, James Dougherty Credit: EPA

23.Marilyn whitened her skin with hormone cream, one side effect of which was to encourage the growth of blonde down on her face; Marilyn would not remove this peach fuzz, believing that it gave her face a soft glow on camera.

24. She was never nominated for an Academy Award, but she was voted the “Oomph Girl” at Emerson Junior High in 1941; crowned Castroville’s first Artichoke Queen in 1948; and was Stars and Stripes magazine’s Miss Cheesecake of 1950.

25. She was named “The Most Advertised Girl in the World” by the Advertising Association of the West in 1953. Among the brands she represented were American Airlines, Kyron Way Diet Pills, Pabst Beer, Tan-Tan Suntan Lotion and Royal Triton Oil.

26. In 1950, Johnny Hyde, her agent, paid for her to have two plastic surgeries: a tip rhinoplasty (reshaping the soft cartilage at the end of her nose); and a chin implant.

27. She was an early devotee of yoga, and was taught by Indra Devi, a Swedish-Russian Bollywood film star who also taught Greta Garbo and Gloria Swanson.

28. Marilyn’s intervention got Ella Fitzgerald her first major engagement at a Los Angeles nightclub. In 1955 the colour bar was still in force, but Marilyn convinced the management to let Fitzgerald play by promising to sit in the front row for a week.

29.Marilyn was only the second woman to head her own production company (Mary Pickford was the first).

30.Marilyn had a fixation on Clark Gable, her co-star in The Misfits; as a young girl, Marilyn dreamed that he was her father. When he died, she said that she cried for two days.

31.She preferred to go naked. Among female studio employees – wardrobe mistresses, hairdressers, make-up artists – she often went without clothes. She gave interviews in the nude and often went out wearing nothing under the black mink that Joe DiMaggio had given her.

32.Writers loved her.Jean-Paul Sartre wanted her to play the role of a hysterical patient in the film Freud, for which he wrote the first draft of a screenplay; she was Truman Capote’s first choice for the part of Holly Golightly in Breakfast at Tiffany’s.

33. Marilyn’s death was ruled a “probable suicide”, but toxicology tests were only carried out on her liver. When the deputy coroner, Thomas Noguchi, tried to obtain her other organs for testing, he was told they’d been destroyed.

34.Veronica Hamel, an actress, bought Marilyn’s house in 1972. She claimed that when she was renovating the house she discovered an extensive system of wire-taps.

35. Marilyn’s hero was Abraham Lincoln: “I used to read everything I could find about him,” she wrote in her (ghosted) autobiography, My Story. “He was the only famous American who seemed most like me, at least in his childhood.”

36. The books she was reading at the time of her death were Harper Lee’s To Kill a Mockingbird and Captain Newman MD, a novel by Leo Rosten based on the life of Monroe’s psychiatrist, Ralph Greenson.

37.Two men claimed paternity of Marilyn on their deathbeds: C Stanley Gifford, who both Marilyn and her mother believed was her father, but who refused to meet Marilyn when she was alive; and Edward Mortensen, who was married to her mother at the time of her birth, and whose (misspelled) surname appears on her birth certificate.

38. She was athletic. As a young married woman on Catalina Island in the early Forties, she studied weightlifting with a former Olympic champion named Howard Corrington. She later went tandem surfing with a boyfriend, Tommy Zahn, balancing on his shoulders as they cut through the waves.

39. She was a talented producer. Marilyn Monroe Productions, which she formed in 1955 with Milton Greene, the photographer, only solely produced one film, The Prince and the Showgirl. Marilyn showed her nous in winning the script: she managed to wangle a meeting with the writer, Terence Rattigan, in New York, where he was stopping over en route to Hollywood to discuss the script with the director William Wyler, luring him from the airport to a downtown bar. When Wyler failed to make him a concrete offer, Rattigan went with Monroe.

40. Many of her friends believed she was murdered. Among the potential suspects: Robert Kennedy (with whom she had had an affair); John F Kennedy (ditto); mafioso Sam Giancana; the FBI; the CIA; her psychiatrist, Ralph Greenson.

41. During the filming of Let’s Make Love, Marilyn’s no-shows added 28 days to the shooting time and $1 million to the budget.

Allan 'Whitey' Snyder applying Marilyn Monroe's makeup on the set of 'Let's Make Love' Credit: AP

42. Her career in front of the camera began when she was discovered working on the assembly line at Radioplane, a munitions factory, by a photographer called David Conover.

43. Arthur Miller’s play After the Fallis generally thought to be a thinly veiled portrayal of his marriage to Marilyn. The writer James Baldwin walked out of the play because he thought that “Maggie”, the Monroe character, was written so cruelly.